In a Long Term Evolution (LTE) system, an access network device sends downlink data to a same terminal device on at least one of multiple carriers. For downlink data on each carrier, the terminal device separately performs acknowledgment and generates hybrid automatic repeat request-acknowledgment HARQ-ACK information. If acknowledgment succeeds, the terminal device returns acknowledgment information ACK. If acknowledgment fails, the terminal device returns negative acknowledgment information NACK. The terminal device sends each piece of acknowledgment information to the access network device on a same uplink channel. In addition, the access network device sends a reference signal to the terminal device on each carrier, so that the terminal device detects the reference signal on each carrier to obtain channel state information (CSI) corresponding to each carrier.
In the prior art, the access network device indicates, by using preconfigured information, a subframe location (which is determined by a subframe offset for feeding back CSI and a period for feeding back the CSI) at which the terminal device feeds back periodic CSI and specific content of the periodic CSI fed back at each location for feeding back the periodic CSI. Herein, the acknowledgment information and/or the CSI are all referred to as uplink control information (UCI). Therefore, UCI fed back by the terminal device to the access network device on the uplink channel in some subframes includes only acknowledgment information or includes only periodic CSI information, while UCI fed back in some subframes includes both acknowledgment information and CSI. Because a quantity of bits of CSI fed back by the terminal device in each subframe for feeding back the periodic CSI is not constant, quantities of bits of UCI fed back by the terminal device in different subframes are different. The access network device allocates multiple uplink channels to the terminal device in advance, and before the terminal device feeds back UCI, the access network device sends dynamic indication information to the terminal device. The dynamic indication information specifies an uplink channel on which the terminal device feeds back the UCI.
As a quantity of uplink channels allocated by the access network device to the terminal device in advance increases continuously, a quantity of bits of the dynamic indication information delivered by the access network device increases continuously, leading to relatively large consumption of downlink channel resources. In addition, a capacity of the uplink channel specified by the access network device for the terminal device by using the dynamic indication information does not meet a size of the UCI. As a result, utilization of the uplink channel is relatively low or UCI bits are discarded.